- base64_encode: documentation ( source)
- mb_encode_mimeheader: documentation ( source)
- mb_internal_encoding: documentation ( source)
<?php
mb_internal_encoding('UTF-8');
echo 'Subject: ', mb_encode_mimeheader('❤', 'UTF-8', 'B');
echo 'Subject: '."=?utf-8?B?" . base64_encode("❤") . "?=";